In the manufacture of footwear it is customary to last the upper material over a last. This is especially needed when uppers of leather are used, because such leather has no uniform stretch. Lasting is performed either on machines attaching the upper to an insole, most of the time while over the last, a replica of the human foot, or by using a last that is part of a molding machine. When using molding machines, one can dispense with the use of insoles or socklinings and obtain the tightening of the upper over the last by means of a welt-like strip, as described in U.S. Pat. No. 4,073,023 in which I appear as co-inventor.
Recent developments in the hide and leather market have resulted in a markable increase in the price of leather, which has led the footwear industry to adopt man-made materials as a substitute of the leather of the upper. The consumer, however, complains that such man-made materials, especially plastics supported by fabric yard material, are hot on the foot, although the use of such textile-supported plastics allow manufacturers to keep prices at a lower level than would be the case if, in today's market, leather would be used.